A humanized anti-IGF-1R monoclonal antibody (R1507) and/or metformin enhance gemcitabine-induced apoptosis in pancreatic cancer cells

Pancreatic cancer is a disease with a dismal prognosis and treatment options are limited. This study investigated the interaction of gemcitabine with R1507 and/or metformin and the induction of an inhibitor of apoptosis protein by this com-bination. Pancreatic cancer cells were treated with gemcitabine, R1507 and metformin alone or in combination. The effects of treatments were evaluated for cell proliferation, apoptosis, and the expression of genes related to inhibition of apoptosis and chemotherapy resistance. Combination of gemcitabine with R1507 and/or metformin additively interacted with the inhibition of cell proliferation in human pancreatic ductal adenocarcinoma cell lines, SUIT-2 and MIAPaCa-2 with differential gemcitabine resistance, and assessment of apoptosis demonstrated that drug associations increased the apoptotic index in both cell lines. Treatment with gemcitabine induced the expression of survivin and XIAP in both cell lines, indicating the induction of chemoresistance. In conclusion, these data demonstrate that the combination of gemcitabine with R1507 and/or metformin has an additive effect in pancreatic cancer cell lines with differential sensitivity to gemcitabine; however, gemcitabine may induce chemotherapy resistance.